Writing instrument



FIG. 1 is a front elevational view of a writing instrument showing my new design;

FIG. 2 is a rear elevation view;

FIG. 3 is a left side elevational view, the right side being a mirror image thereof;

FIG. 4 is a bottom plan view thereof; and,

FIG. 5 is a top plan view thereof.

In FIGS. 1, 2 and 3, the tip of the writing instrument has been depicted by broken lines for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a writing instrument, as shown and described. 